Observation of magnetization reversal in epitaxial Gd0.67Ca0.33MnO3 thin films

TL;DR

This study reports the observation of magnetization reversal in epitaxial Gd0.67Ca0.33MnO3 thin films, revealing unique magnetic behavior influenced by strain and exchange interactions, with potential implications for magnetic device applications.

Contribution

First observation of magnetization reversal in epitaxial Gd0.67Ca0.33MnO3 thin films, highlighting the effects of strain and exchange interactions on magnetic properties.

Findings

Magnetization reverses below Tc under small fields

Reversal occurs at 7 K in FC and above 83 K in ZFC

Higher magnetic fields suppress magnetization sign change

Abstract

High quality epitaxial thin films of Gd0.67Ca0.33MnO3 have been deposited onto (100) SrTiO3 substrates by pulsed-laser deposition. Enhanced properties in comparison with bulk samples were observed. The magnetic transition temperature (Tc) of the as-grown films is much higher than the corresponding bulk values. Most interestingly, magnetization measurements performed under small applied fields, exhibit magnetization reversals below Tc, no matter whether the film is field-cooled (FC) or zero-field-cooled (ZFC). A rapid magnetization reversal occurs at 7 K when field cooled, while as for the ZFC process the magnetization decreases gradually with increasing temperatures, taking negative values above 7 K and changing to positive values again, above 83 K. In higher magnetic fields the magnetization does not change sign. The reversal mechanism is discussed in terms of a negative exchange f-d interaction and magnetic anisotropy, this later enhanced by strain effects induced by the lattice mismatch between the film and the substrate.